It sounds like my daughter when she hates her food, and has to be forced to swallow..omg..lol..he just hates it, try something else..if he is forcing himself to eat, it's usually because he hates the food, try the Omega One, they do float, and The Hakari Gold, all my rescues who were sick, all ate within the first pellet..try one of those..

Yes, he may just not like the NLS at all, like Lelei said. I've more recently switched over to Omega One because the pellets I was feeding before, HBH Betta bites(which is what I have been feeding my fish for years because that was literally all that my LPS sold where I used to live for a long time)one of my boys, Nine, just decided he didn't like them anymore and stopped eating. Thankfully I had some Omega One on the shelf, he started eating those after taking a few days to get used to it, and then I just....switched everyone(the rest of them are such little pigs they could care less what I feed them. xD)to Omega One. I'd always had issues with HBH being a little on the big side anyway.
And I might even have to switch brands again, or feed one of my guys a completely different brand because I'm STILL having issues with my one being a brat about eating after two weeks. Lol, so I can definitely understand your frustration.

But anyway, there are plenty of other brands you can try and see if he takes to any of them. Lelei mentioned a couple, and I think I mentioned a couple more in my previous post. Whatever pellet brand(s) you pick up, I'd suggest trying them for at least a couple of days before giving up. It will take time for him to get used to the new food probably, especially if hes a more picky eater.
And then as backup plans, if crushing doesn't work, you can also try the soaking and fresh garlic method.

I gotta tell ya, I just recently switched to the Omega one for variety as all my fish are used to the Hakari Gold, and eat them with a vengence, so just to see if they would eat the Omega, I have played a trick on them, none of them compained..(spit out the food) only one, My Crimson, knew right away..and spit it right out..It was funny..so I kept him on the Hakari, these fish are incredibly picky..and just like kids, can't put anything over on them..hahaha..

I gotta tell ya, I just recently switched to the Omega one for variety as all my fish are used to the Hakari Gold, and eat them with a vengence, so just to see if they would eat the Omega, I have played a trick on them, none of them compained..(spit out the food) only one, My Crimson, knew right away..and spit it right out..It was funny..so I kept him on the Hakari, these fish are incredibly picky..and just like kids, can't put anything over on them..hahaha..

LOL Lelei...that is so true these little guys are so smart and they notice everything !!!!